1. Field of the Invention
The present invention relates to a device for collecting samples of a liquid in a tank or in a chemical reaction vessel, and more particularly to a device comprising a cup, which cup is provided with a cavity and with openings for filling and for outflow, and which is fitted, so as to be moveable by the action of a piston, in a guide tube which is fitted onto a tank or onto a chemical reaction vessel.
2. Description of Related Art
Devices for the collection of samples are utilized in the chemical industry for collecting samples of those liquids which are contained in tanks or in chemical reaction vessels for the purpose of performing laboratory analyses. These liquids are most often very toxic and volatile; and consequently, the collecting of samples necessitates a great many precautions, on the one hand, to spare the user from having to come into contact with the toxic liquid, and, on the other hand, to prevent pollution resulting from the release of a toxic and volatile liquid into the surrounding air.
The heretofore known embodiments of devices for collecting samples present a great many disadvantages. In fact, the embodiments of prior art generally consist of devices provided with conduits which collect the liquid by means of suction mechanisms or aspirating pumps, all of which occasionally makes it impossible to collect the sample due to the fact that the liquid fails to rise in the collecting device when the reaction vessel is subjected to vacuum conditions or when the vapor tension of the liquid is low. There are embodiments utilizing gases which are intended to aspirate or to drive the sample of liquid to outside of the reaction vessel; however, these embodiments present a disadvantage linked to the use of a gas under pressure, the chief hazard of which may be the bursting of a seam or joint, which may constitute a grave peril for the operator in case the gas were to escape outwards. What is more: all these devices of prior art exhibit a major drawback in that they throw out into the atmosphere a significant quantity of polluted gases. An exemplified embodiment of a piston being displaceable in a tube is already known from U.S. Pat. No. 5,029,484; however, this device presents the disadvantage of not being able to function except in an open appliance--which is to say that it can only function correctly if the external pressure is equal to the pressure prevailing in the tank or in the chemical reaction vessel.